Low-color stiff PVB laminates

Abstract

The present invention describes laminate articles comprising a stiff, low-color PVB sheet having a YID of less than 12 and having a low concentration of plasticizer in the PVB composition, wherein the sheet is prepared from a composition that includes a PVB bleaching compound. A sheet of the present invention is useful for making glass laminates useful for parts in making cars, boats, trains, buildings, display cases, and other articles that utilize transparent glass laminates.

1. A process for preparing a low color poly(vinyl butyral) sheet comprising the steps:
 (I) admixing polyvinyl alcohol, butyraldehyde, an acid or mixture of acids, water, and sodium dioctyl sulfosuccinate to form a mixture, 
 (II) stabilizing the mixture obtained in step (I) by (a) raising the pH of the mixture to at least pH 10, (b) isolating polyvinyl butyral resin by draining liquid, (c) washing the poly(vinyl butyral) resin with neutral pH water; 
 (III) plasticizing the polyvinyl butyral resin with a finite amount of less than 30 pph of plasticizer based on the dry weight of the poly(vinyl butyral) resin; 
 (IV) mixing (a) a polyvinyl butyral bleaching compound selected from the group consisting of organic bisulfites, inorganic bisulfites and sulfosuccinates and, optionally, (b) an antioxidant and a UV light stabilizer, with the poly(vinyl butyral) resin; and 
 (V) extruding the polyvinyl butyral after completion of steps (III) and (IV) at a temperature of from about 225° C. to about 245° C. to obtain the polyvinyl butyral sheet, the polyvinyl butyral sheet having a T g  in the range of from about 35° C. to about 60° C. and a YID of less than 12. 
 
     
     
       2. The process of  claim 1  wherein the sodium dioctyl sulfosuccinate is included in amount of from about 0.01 to about 0.85 pph by weight, based on the weight of polyvinyl alcohol. 
     
     
       3. The process of  claim 1  further comprising laminating the polyvinyl butyral sheet to glass. 
     
     
       4. The process of  claim 1  wherein the plasticizer is present in an amount of from about 5 to about 30 pph. 
     
     
       5. The process of  claim 2  wherein the plasticizer is present in an amount of from about 15 to about 30 pph. 
     
     
       6. The process of  claim 5  wherein the plasticizer is present in an amount of from about 18 to about 22 pph. 
     
     
       7. The process article of  claim 3  wherein the laminate comprises at least one layer of the polyvinyl butyral sheet and at least one layer of glass wherein the polyvinyl butyral sheet layer has a thickness in the range of from about 0.254 mm to about 1.6 mm. 
     
     
       8. The process of  claim 7  wherein the laminate is useful as: architectural glass; automobile glass; train glass; or boat glass. 
     
     
       9. The process of  claim 1  wherein the plasticizer is selected from the group consisting of triethylene glycol di(2-ethylhexanoate), tetraethylene glycol diheptanoate, dibutyl sebacate, and mixtures thereof. 
     
     
       10. The process of  claim 2  wherein the sodium dioctyl sulfosuccinate is included in amount of from about 0.01 to about 0.85 pph by weight, based on the weight of polyvinyl alcohol. 
     
     
       11. The process of  claim 2  wherein the sodium dioctyl sulfosuccinate is included in amount of from about 0.05 to about 0.80 pph by weight, based on the weight of polyvinyl alcohol. 
     
     
       12. The process of  claim 2  wherein the sodium dioctyl sulfosuccinate is included in amount of from about 0.15 to about 0.75 pph by weight, based on the weight of polyvinyl alcohol. 
     
     
       13. The process of  claim 2  wherein the sodium dioctyl sulfosuccinate is included in amount of from about 0.15 to about 0.70 pph by weight, based on the weight of polyvinyl alcohol. 
     
     
       14. The process of  claim 1  wherein the antioxidant is included in an amount of from about 0.01 to about 0.6%, based on the total weight of the sheet. 
     
     
       15. The process of  claim 14  wherein the antioxidant is a bis-phenolic antioxidant. 
     
     
       16. The process of  claim 1  wherein the bleaching compound is a dialkyl sulfosuccinate. 
     
     
       17. The process of  claim 2  wherein the bleaching compound is sodium dioctyl sulfosuccinate. 
     
     
       18. The process of  claim 1  wherein the polyvinyl butyral bleaching compound is selected from the organic bisulfites. 
     
     
       19. The process of  claim 1  wherein the polyvinyl butyral bleaching compound is selected from the inorganic bisulfites. 
     
     
       20. The process of  claim 1  wherein the polyvinyl butyral bleaching compound is present in an amount of from about 0.01 to about 0.85 parts per hundred, based on the weight of polyvinyl alcohol used in the preparation of the polyvinyl butyral resin. 
     
     
       21. The process of  claim 17  wherein the polyvinyl butyral bleaching compound is present in an amount of from about 0.10 to about 0.75 parts per hundred, based on the weight of polyvinyl alcohol used in the preparation of the polyvinyl butyral resin. 
     
     
       22. A process for preparing a low color polyvinyl butyral sheet comprising the steps:
 (I) admixing polyvinyl alcohol, butyraldehyde, an acid or mixture of acids, water, and sodium dioctyl sulfosuccinate at a temperature of 5 to 100° C. to form a mixture; 
 (II) stabilizing the mixture obtained in step (I) by (a) raising the pH of the mixture to at least pH 10, (b) isolating polyvinyl butyral resin by draining liquid, and (c) washing the polyvinyl butyral resin with neutral pH water; 
 (III) plasticizing the polyvinyl butyral resin with about 5 to about 30 pph of plasticizer, based on the dry weight of the polyvinyl butyral resin, wherein the plasticizer is selected from the group consisting of triethylene glycol di(2-ethylhexanoate), tetraethylene glycol diheptanoate, dibutyl sebacate, and mixtures thereof; and 
 (IV) extruding the polyvinyl butyral resin at a temperature of from about 225° C. to about 245° C. to obtain a polyvinyl butyral sheet having a glass transition temperature (T g ) in the range of from about 35° C. to about 60° C. and a YID of less than 12. 
 
     
     
       23. A process for preparing a low color polyvinyl butyral sheet comprising the steps:
 (I) admixing polyvinyl alcohol, butyraldehyde, an acid or mixture of acids, water, and sodium dialkyl sulfosuccinate to form a mixture; 
 (II) stabilizing the mixture obtained in step (I) by (a) raising the pH of the mixture to at least pH 10, (b) isolating polyvinyl butyral resin by draining liquid, and (c) washing the polyvinyl butyral resin with neutral pH water; 
 (III) plasticizing the polyvinyl butyral resin with about 5 to about 30 pph of plasticizer selected from the group consisting of diesters obtained by (a) the reaction of triethylene glycol or tetraethylene glycol with aliphatic carboxylic acids having from 6 to 10 carbon atoms and (b) the reaction of sebacic acid with aliphatic alcohols having from 1 to 18 carbon atoms, and mixtures thereof, based on the dry weight of the polyvinyl butyral resin; and 
 (IV) extruding the polyvinyl butyral resin at a temperature of from about 225° C. to about 245° C. to obtain a polyvinyl butyral sheet. 
 
     
     
       24. The process of  claim 23  wherein the plasticizer is selected from the group consisting of the diesters obtained by the reaction of triethylene glycol or tetraethylene glycol with aliphatic carboxylic acids having from 6 to 10 carbon atoms.